Sensor window

ABSTRACT

A sensor window may include a substrate and a set of layers disposed onto the substrate. The set of layers may include a first subset of layers of a first refractive index and a second set of layers of a second refractive index different from the first refractive index. The set of layers may be associated with a threshold transmissivity in a sensing spectral range. The set of layers may be configured to a particular color in a visible spectral range and may be associated with a threshold opacity in the visible spectral range.

RELATED APPLICATION(S)

This application is a continuation of U.S. patent application Ser. No.16/103,625, filed on Aug. 14, 2018 (now U.S. Pat. No. 10,948,640), whichclaims priority under 35 U.S.C. § 119 to U.S. Provisional PatentApplication No. 62/642,354, filed on Mar. 13, 2018, the contents ofwhich are incorporated by reference herein in their entirety.

BACKGROUND

An optical receiver, such as a sensor element array, may receive lightthat is directed toward the optical receiver. For example, in an objectdetection system, a sensor element array may be utilized to captureinformation about one or more wavelengths of light. The sensor elementarray may include a set of sensor elements (e.g., optical sensors,spectral sensors, and/or image sensors) that capture the informationabout the one or more wavelengths of light. An optical transmitter mayemit light that is directed toward an object. For example, in the objectdetection system, the optical transmitter may transmit near-infraredlight toward an object, and the near-infrared light may be reflected offthe object toward the sensor element array. In this case, based on theinformation captured by the sensor element array, the object may bedetected. For example, in a vehicle context, a device may use theinformation to generate a three dimensional representation of theobject, and to identify a proximity of the object, thereby enablingobject avoidance by the vehicle.

In another example, information captured by an optical receiver, such asa sensor element array, may be used to recognize a characteristic of anobject (e.g., a distance to the object, a size of the object, a shape ofthe object, a spectroscopic signature of the object, a type of theobject, a speed of the object, etc.), an identity of a person, acharacteristic of the person (e.g., a height, a weight, a speed ofmovement, a health characteristic, etc.), and/or the like. However,during transmission of the near-infrared light toward the user or objectand/or during reflection from the user or object toward the opticalreceiver, ambient light may interfere with the near-infrared light.Thus, the optical receiver may be optically coupled to an opticalfilter, such as a bandpass filter, to filter ambient light and to allownear-infrared light to pass through toward the optical receiver.Moreover, when performing sensing of multiple wavelengths of light, afilter may be provided to ensure that each wavelength of light, of themultiple wavelengths of light, is directed to a different sensor elementof a sensor element array.

SUMMARY

According to some possible implementations, a sensor window may includea substrate and a set of layers disposed onto the substrate. The set oflayers may include a first subset of layers of a first refractive indexand a second set of layers of a second refractive index different fromthe first refractive index. The set of layers may be associated with athreshold transmissivity in a sensing spectral range. The set of layersmay be configured to a particular color in a visible spectral range andmay be associated with a threshold opacity in the visible spectralrange.

According to some possible implementations, an optical filter mayinclude a plurality of layers. The plurality of layers may include a setof high refractive index layers associated with a first refractive indexand a set of low refractive index layers associated with a secondrefractive index that is less than the first refractive index. Theplurality of layers may form a plurality of channels to direct aplurality of wavelengths of light. The plurality of layers may beassociated with a threshold transmissivity in a sensing spectral rangeand a threshold opacity in a visible spectral range.

According to some possible implementations, a system may include a setof optical sensors disposed on or in a substrate and a sensor windowdeposited in an optical path of the set of optical sensors. The sensorwindow may include at least one layer configured to provide greater than80% opacity at a first spectral range and for angles of incidence fromapproximately 0 degrees to approximately 45 degrees and to providegreater than 80% transmissivity at a second spectral range, which isdifferent from the first spectral range, and for angles of incidencefrom approximately 0 degrees to approximately 45 degrees.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

FIG. 1 is a diagram of an example implementation of a sensor windowdescribed herein.

FIG. 2 is a diagram of an example implementation of an optical systemthat includes a sensor window described herein.

FIG. 3 is a diagram of an example implementation of a sensor windowdescribed herein.

FIGS. 4A-4E are diagrams of an example of characteristics of a sensorwindow described herein.

FIGS. 5A-5D are diagrams of an example of characteristics of a sensorwindow described herein.

FIGS. 6A-6D are diagrams of an example of characteristics of a sensorwindow described herein.

FIGS. 7A-7C are diagrams of an example of characteristics of a sensorwindow described herein.

FIGS. 8A-8E are diagrams of an example of characteristics of a sensorwindow described herein.

DETAILED DESCRIPTION

The following detailed description of example implementations refers tothe accompanying drawings. The same reference numbers in differentdrawings may identify the same or similar elements.

A window may be provided to separate an internal environment from anexternal environment and to enable light to pass through from theexternal environment to the internal environment, from the internalenvironment to the external environment, and/or the like. For example,in a vehicle context, such as for a car, a windshield window may beprovided to protect a vehicle operator from environmental conditions,such as a rain condition, a wind condition, a dust condition, a debriscondition, and/or the like. The windshield window may be manufacturedfrom a material that provides durability and that enables light to passthrough to enable the vehicle operator to operate the vehicle.

An optical system may be disposed behind the windshield window toprotect the optical system from the external environment. For example,in a vehicle context, an object recognition sensor may be disposedbehind a windshield, a headlight, and/or the like to protect the objectrecognition sensor. Similarly, in a security context, a facialrecognition sensor may be disposed behind a window to protect the facialrecognition sensor from being adjusted by unauthorized persons. However,the window may enable unauthorized persons to see the optical system.For example, an unauthorized person may see the optical system behind awindow, and may cover the window, damage the window and/or the opticalsystem, avoid a line of sight of the optical system, and/or the like,thereby reducing an effectiveness of the optical system. Similarly, avehicle owner may forgo installing an object recognition sensor in anautomobile because of a negative aesthetic impact to the automobile fromthe optical system being visible to other persons, thereby forgoingsafety benefits from the object recognition sensor.

Some windows may be colored to reduce a visibility of a sensor systemdisposed behind the window. For example, in the vehicle context, tintedglass may be used to hide the object recognition sensor from view to anexternal person. Similarly, in the security context, a color pigment maybe applied to glass to hide a facial recognition sensor disposed behindthe glass. However, using pigment colored glass or tinted glass mayrequire greater than a threshold glass thickness to achieve opaqueness,which may result in an excessive size for installation, may reduce anamount of light that is directed to an optical system or is provided bythe optical system, and/or the like. Furthermore, a color pigment basedcolored glass may lack a sharp transition between opaqueness in visiblelight wavelengths and transmissivity in sensing light wavelengths (e.g.,near-infrared wavelengths, mid-infrared wavelengths, and/or the like).The lack of the sharp transition may reduce a sensing capability insensing wavelengths relatively close to visible light wavelengths,thereby reducing an effectiveness of the optical system.

Some implementations, described herein, may provide a color-matchedsensor window for an optical system. For example, a sensor window may beconfigured, such as using alternating high refractive index materiallayers and low refractive index material layers, to be transmissive tosensing wavelengths and opaque to visible light wavelengths. In thisway, the sensor window may be configured color-selectively to enableintegration into, for example, a vehicle, a secure housing, and/or thelike. Moreover, the sensor window may be associated with less than athreshold thickness and with a relatively sharp transition betweentransmissivity at sensing wavelengths and opaqueness at visible lightwavelengths, thereby improving performance of an optical systemassociated with the sensor window. Furthermore, based on being colorconfigurable, the sensor window may be color-matched to an externalenvironment, thereby reducing a likelihood that an optical system isinstalled (e.g., into a vehicle, as a security feature, etc.) relativeto non-color-selectively configurable sensor windows.

FIG. 1 is a diagram of an example implementation 100 described herein.As shown in FIG. 1, example 100 may include a vehicle 110, a sensorwindow 120, and a sensor 130.

Although some implementations, described herein, are describe in termsof a sensing system in a vehicle deployment, other systems in otherdeployments are possible, such as a communications system (e.g., a Li-Fisystem), a biometric system, a security system, a health monitoringsystem, an object identification system, a spectroscopic identificationsystem, a LIDAR system, and/or the like in a fixed deployment, awearable deployment, and/or the like.

As further shown in FIG. 1, vehicle 110 may be within a thresholdproximity of an object 140 (e.g., a stop sign). As shown by referencenumbers 150 and 160, sensor 130 may transmit an optical signal towardobject 140, and the optical signal may be reflected toward sensor 130.For example, sensor 130 may transmit a near-infrared signal, and mayreceive a reflected near-infrared signal based on object 140 reflectingthe near-infrared signal. In this case, sensor 130 may determine acharacteristic of object 140 based on the reflected near-infraredsignal. For example, sensor 130 may determine a proximity of object 140,a size of object 140, a type of object of object 140, and/or the likebased on the reflected near-infrared signal.

In some implementations, sensor window 120 may be associated with aparticular color. For example, based on a type of layers, a thickness oflayers, an order of layers, and/or the like, sensor window 120 may beconfigured to pass near-infrared light, to absorb a first set of colorsof visible light, and to reflect a second set of colors of visiblelight. In this case, based on configuring the second set of colors tomatch a surface adjacent to sensor window 120 (e.g., based on causingsensor window 120 to reflect a shade of red matching vehicle 110),sensor window 120 may be hidden from view. Moreover, based onconfiguring sensor window 120 to pass near-infrared light, sensor window120 may enable sensor 130 to transmit the near-infrared signal andreceive the reflected near-infrared signal without the near-infraredlight being blocked by sensor window 120. In this way, sensor window 120enables functioning of a sensor system including sensor 130, protectssensor 130 from environment degradation, and hides sensor 130 from view,thereby improving both functioning of sensor 130 and aesthetics ofvehicle 110.

As indicated above, FIG. 1 is provided merely as an example. Otherexamples are possible and may differ from what was described with regardto FIG. 1.

FIG. 2 is a diagram of an example implementation 200 described herein.As shown in FIG. 2, example implementation 200 includes a sensor system.The sensor system may be a portion of an optical system, and may providean electrical output corresponding to a sensor determination. The sensorsystem includes a sensor window 210, which is disposed on a substrate220, and an optical sensor 230. In some implementations, sensor window210 may be an optical filter that performs a filtering functionality.For example, sensor window 210 may include alternating high refractiveindex material layers and low refractive index material layers toprovide color selectivity and to direct light to multiple sensorelements of optical sensor 230 associated with multiple wavelengthchannels.

Although some implementations, described herein, may be described interms of a sensor window in a sensor system, implementations describedherein may be used in another type of system, may be used external to asensor system, and/or the like.

As further shown in FIG. 2, and by reference number 240, an inputoptical signal is directed toward sensor window 210. The input opticalsignal may include but is not limited to light associated with aparticular spectral range (e.g., a near-infrared spectral range, amid-infrared spectral range, a visible spectral range, and/or the like).For example, an optical transmitter may direct the light toward opticalsensor 230 to permit optical sensor 230 to perform a measurement of thelight (e.g., the optical transmitter may direct the light toward anobject and the light may be reflected toward optical sensor 230). Inanother example, the optical transmitter may direct another spectralrange of light for another functionality, such as a testingfunctionality, a sensing functionality, a communications functionality,and/or the like.

As further shown in FIG. 2, and by reference number 250, a first portionof the input optical signal with a first spectral range is not passedthrough by sensor window 210. For example, dielectric filter stacks ofdielectric thin film layers, which may include high index materiallayers and low index material layers of sensor window 210, may cause thefirst portion of the input optical signal to be reflected in a firstdirection, to be absorbed, and/or the like. In some implementations, thefirst portion of the input optical signal may include first light thatis reflected to cause sensor window 210 to appear to a viewer as aparticular color and second light that is absorbed. In someimplementations, the first portion of the input optical signal may be athreshold portion of light incident on sensor window 210 not included ina bandpass of sensor window 210, such as greater than 95% of light,greater than 99% of light, and/or the like in a visible spectral range.

As further shown in FIG. 2, and by reference number 260, a secondportion of the input optical signal is passed through by sensor window210. For example, sensor window 210 may pass through the second portionof the input optical signal with a second spectral range in a seconddirection toward optical sensor 230. In this case, the second portion ofthe input optical signal may be a threshold portion of light incident onsensor window 210 within a bandpass of sensor window 210, such asgreater than 50% of incident light, greater than 90% of light, greaterthan 95% of light, greater than 99% of light, and/or the like in anear-infrared spectral range. In some implementations, sensor window 210may be associated with multiple component filters associated withmultiple spectral ranges. For example, based on varying a thickness ofsensor window 210, different portions of sensor window 210 may passdifferent wavelengths of light to different sensor elements of opticalsensor 230, thereby enabling multispectral sensing.

As further shown in FIG. 2, and by reference number 270, based on thesecond portion of the input optical signal being passed to opticalsensor 230, optical sensor 230 may provide an output electrical signalfor the sensor system, such as for use in imaging, detecting thepresence of an object, identifying a person, performing a measurement,facilitating communication, and/or the like. In some implementations,another arrangement of sensor window 210 and optical sensor 230 may beutilized. For example, rather than passing the second portion of theinput optical signal collinearly with the input optical signal, sensorwindow 210 may direct the second portion of the input optical signal inanother direction toward a differently located optical sensor 230.

As indicated above, FIG. 2 is provided merely as an example. Otherexamples are possible and may differ from what was described with regardto FIG. 2.

FIG. 3 is a diagram of an example optical filter 300. FIG. 3 shows anexample stackup of an optical filter that may be utilized as a sensorwindow described herein. As further shown in FIG. 3, optical filter 300includes an optical filter coating portion 310 and a substrate 320.

Optical filter coating portion 310 includes a set of optical filterlayers. For example, optical filter coating portion 310 includes a firstset of layers 330-1 through 330-N+1 (N≥1) and a second set of layers340-1 through 340-N. In another example, optical filter coating portion310 may be a single type of layer (e.g., one or more layers 330), threeor more types of layers (e.g., one or more layers 330, one or morelayers 340, and one or more of one or more other types of layers),and/or the like. In some implementations, optical filter coating portion310 may be disposed on a single side of substrate 320. In someimplementations, optical filter coating portion 310 may bediscontinuous. For example, optical filter coating portion 310 may bedisposed on multiple sides of substrate 320. In this case, a first setof layers of optical filter coating portion 310 may be disposed on a topside of substrate 320 and a second set of layers of optical filtercoating portion 310 may be disposed on a bottom side of substrate 320 tocollectively provide a color-selectively functionality, a passbandfunctionality, an out-of-band block functionality, an anti-reflectancecoating functionality, a polarization control functionality, and/or thelike. Additionally, or alternatively, optical filter coating portion 310may include a first set of layers and a second set of layers separatedby and sandwiching one or more intermediate layers.

In some implementations, layers 330 may include a set of layers of ahigh refractive index material (H layers), such as silicon layers,hydrogenated silicon layers, silicon-germanium (SiGe) layers, germaniumlayers, hydrogenated germanium layers, hydrogenated silicon-germaniumlayers, and/or the like. In some implementations, layers 330 may beassociated with a refractive index of greater than approximately 3.0,greater than approximately 3.5, greater than approximately 3.6, greaterthan approximately 3.8, greater than approximately 4.0, and/or the like.Although some layers may be described as a particular material, such asSiGe, some layers may include (small quantities of) phosphor, boron,nitride, hydrogen, a noble gas, and/or the like.

In some implementations, layers 330 may include a set of layers of ametal or metal alloy material. For example, layers 330 may be silverlayers. Additionally, or alternatively, layers 330 may be silver alloylayers. For example, a silver alloy may be used that includesapproximately 0.5 wt % gold, approximately 0.5 wt % tin, and/or the liketo provide improved corrosion resistance relative to other materials. Insome implementations, layers 330 may be aluminum layers. In someimplementations, layers 330 may include gold layers, platinum layers,palladium layers, alloy layers thereof, and/or the like. In someimplementations, layers 330 may have different thicknesses. For example,a first metal layer may have a first thickness and a second metal layermay have a second thickness. In this case, the metal layers each mayhave a physical thickness of between approximately 5 nm andapproximately 50 nm, of between approximately 10 nm and approximately 35nm, and/or the like.

In some implementations, layers 340 may include a set of layers of a lowrefractive index material (L layers), such as silicon dioxide layersand/or the like. Additionally, or alternatively, the L layers mayinclude tantalum pentoxide (Ta₂O₅) layers, niobium pentoxide (Nb₂O₅)layers, titanium dioxide (TiO₂) layers, aluminum oxide (Al₂O₃) layers,zirconium oxide (ZrO₂) layers, yttrium oxide (Y₂O₃) layers, siliconnitride (Si₃N₄) layers, a combination thereof, and/or the like. In someimplementations, layer 340 may be associated with a refractive index ofless than approximately 2.7, less than approximately 2.0, less thanapproximately 1.5, and/or the like. In some aspects, a differencebetween a first refractive index of layers 330 and a second refractiveindex of layers 340 may be greater than approximately 1.5, greater thanapproximately 2.0, greater than approximately 2.5, greater thanapproximately 3.0, greater than approximately 3.5, and/or the like. Insome implementations, optical filter coating portion 310 may includelayers 330 of a first material and layers 340 of a second material.

In some implementations, optical filter coating portion 310 may includelayers 330 of multiple materials and/or layers 340 of multiplematerials. For example, optical filter coating portion 310 may include afirst type of layer 330 with a first refractive index, a second type oflayer 330 with a second refractive index, and a layer 340 with a thirdrefractive index. Similarly, optical filter coating portion 310 mayinclude a layer 330 with a first refractive index, a first type of layer340 with a second refractive index, and a second type of layer 340 witha third refractive index. Similarly, optical filter coating portion 310may include multiple types of layers 330 with multiple refractiveindices and multiple types of layers 340 with multiple refractiveindices. Based on using a third type of material, a fourth type ofmaterial, and/or the like, a color, a passband, a filteringfunctionality, and/or the like may be tuned to a higher degree ofconfigurability (e.g., a more granular color configurability, passbandconfigurability, and/or the like) relative to using a single materialfor layers 330 and a single material for layers 340.

In some implementations, optical filter coating portion 310 may beassociated with a particular quantity of layers, m. For example, anoptical filter for use as a sensor window may include a quantity ofalternating high refractive index layers and low refractive indexlayers, such as a range of 2 layers to 200 layers. In someimplementations, optical filter coating portion 310 may be fabricatedusing a sputtering procedure. For example, optical filter coatingportion 310 may be fabricated using a pulsed-magnetron based sputteringprocedure to sputter alternating layers 330 and 340 on a glass substrateor another type of substrate, as described herein. In someimplementations, multiple cathodes may be used for the sputteringprocedure, such as a first cathode to sputter silicon and a secondcathode to sputter germanium or a mix of germanium and silicon, therebyforming a silicon-germanium layer. In some implementations, opticalfilter coating portion 310 may include one or more other types of layersto provide one or more other functionalities, such as a hydrophobiclayer, an oleophobic layer, a protective layer (e.g., a coating disposedon top of optical filter coating portion 310), an anti-reflectancelayer, a heat generating layer (e.g., a layer of material with embeddedelectrical connections to enable heating of optical filter 300), ananti-icing layer, an out of band blocker layer (e.g., to block aparticular spectral range), and/or the like. In some implementations,substrate 320 may be chemically strengthened glass to provide protectionto one or more sensor elements covered by substrate 320.

In some implementations, optical filter coating portion 310 may beannealed using one or more annealing procedures, such as a firstannealing procedure at a temperature of approximately 280 degreesCelsius or between approximately 200 degrees Celsius and approximately400 degrees Celsius, a second annealing procedure at a temperature ofapproximately 320 degrees Celsius or between approximately 250 degreesCelsius and approximately 350 degrees Celsius, and/or the like.

In some implementations, each layer of optical filter coating portion310 may be associated with a particular thickness. For example, layers330 and 340 may each be associated with a thickness of between 1 nm and1500 nm, between 10 nm and 500 nm, and/or the like. Additionally, oralternatively, optical filter 300 may be associated with a thickness ofbetween 50 μm and 10 millimeters (mm), between 1 mm and 5 mm, and/or thelike. In some implementations, at least one of layers 330 and 340 mayeach be associated with a thickness of less than 1000 nm, less than 100nm, or less than 5 nm, and/or the like. Additionally, or alternatively,optical filter coating portion 310 may be associated with a thickness ofless than 100 μm, less than 50 μm, less than 10 μm, less than 5 μm,and/or the like. In some implementations, a layer may be associated withmultiple different thicknesses. For example, to form a set of channels,a thickness of a particular layer (e.g., a spacer layer disposed betweena set of reflectors formed by layers 330 and layers 340) may be variedto cause different wavelengths of light to be directed to differentsensor elements of a sensor element array via different channels. Inthis way, a sensor window may enable use of a multispectral sensor todetermine information regarding multiple wavelengths of light. In someimplementations, optical filter 300 may form at least 1 channel, atleast 2 channels, at least 32 channels, at least 64 channels, at least128 channels, and/or the like to enable sensing of a threshold quantityof wavelengths. In some implementations, multiple channels may beassociated with a common wavelength for sensing by at least one sensorelement aligned to the multiple channels.

In some implementations, optical filter 300 may be associated with aparticular spectral range, such as a near-infrared spectral range, amid-infrared spectral range, and/or the like. For example, opticalfilter 300 may be associated with a spectral range from approximately600 nm to approximately 2500 nm, from approximately 700 nm toapproximately 2000 nm, from approximately 800 nm to approximately 1600nm, and/or the like. In some implementations, optical filter 300 may beassociated with a particular center wavelength, such as a centerwavelength of approximately 940 nm, a center wavelength of approximately1064 nm, a center wavelength of approximately 1550 nm, and/or the like.In some implementations, optical filter 300 may be associated with aparticular channel separation, such as a channel separation of less thanapproximately 50 nm, less than approximately 20 nm, less thanapproximately 10 nm, less than approximately 5 nm, less thanapproximately 1 nm, and/or the like.

In some implementations, optical filter 300 may be associated with aparticular color shift. For example, optical filter 300 may beassociated with a color shift from a first color at a first angle ofincidence (e.g., 0 degrees) to a second color at a second angle ofincidence (e.g., greater than 15 degrees, 30 degrees, 45 degrees, 60degrees, and/or the like) of within 1 ΔE, within 5 ΔE, within 10 ΔE,within 20 ΔE, within 30 ΔE, within 40 ΔE, within 100 ΔE, within 150 ΔE,and/or the like. In some implementations, optical filter 300 may beassociated with a threshold transmissivity, such as greater thanapproximately 50% transmissivity, greater than approximately 80%transmissivity, greater than approximately 90% transmissivity, greaterthan approximately 95% transmissivity, greater than approximately 99%transmissivity, and/or the like a particular spectral range (e.g., asensing spectral range). In some implementations, optical filter 300 maybe associated with a threshold opacity (e.g., based on reflectance,absorption, and/or the like). For example, optical filter 300 may beassociated with an opacity of greater than approximately 50%transmissivity, greater than approximately 80% transmissivity, greaterthan approximately 90% transmissivity, greater than approximately 95%transmissivity, greater than approximately 99% transmissivity, and/orthe like a particular spectral range (e.g., a visible spectral range).In this way, optical filter 300 enables color-selectivity for a sensorwindow and enables sensing by a sensor element disposed in an opticalpath of the sensor window.

As indicated above, FIG. 3 is provided merely as an example. Otherexamples are possible and may differ from what was described with regardto FIG. 3.

FIGS. 4A-4E are diagrams of example characteristics relating to a sensorwindow described herein.

As shown in FIG. 4A, and by chart 400, a transmissivity may bedetermined for a sensor window and a particular spectral range. In thiscase, the sensor window may be a black-colored anti-reflectance sensorwindow disposed on a borosilicate substrate, matched to an airenvironment, and exposed to collimated light. Moreover, the sensorwindow is configured for a spectral range centered at 1550 nm. As shown,at an angle of incidence from approximately 0 degrees to approximately45 degrees, the transmissivity is less than 5% between approximately 400nm and approximately 780 nm and is greater than 95% at approximately1550 nm. In this case, a blocker may be added to an optical filter thatincludes the sensor window to block transmission at, for example, lessthan approximately 1000 nm. As further shown, as a result of thetransmissivity and reflectance, shown in FIG. 4B, a surface with thesensor window may appear a particular color in a visible spectral rangeand may provide anti-reflectance at a desired NIR spectral range atwhich sensing is to be performed.

As shown in FIG. 4B, and by chart 410, a reflectance may be determinedfor the sensor window. In this case, reflectance may be less than 10% inthe visible spectral range (e.g., approximately 390 nm to approximately700 nm) and at angles of incidence from approximately 0 degrees toapproximately 45 degrees resulting in a black color for the sensorwindow across a threshold range of angles of incidence (e.g., fromapproximately 0 degrees to at least approximately 45 degrees).

As shown in FIGS. 4C and 4D, and by charts 420 and 430, respectively, acolor shift at angles of incidence from approximately 0 degrees toapproximately 60 degrees is determined. For example, the sensor windowis associated with a color shift, at angles of incidence fromapproximately 0 degrees to approximately 60 degrees, of less thanapproximately 20 ΔE, at angles of incidence from approximately 0 degreesto approximately 30 degrees of less than 5 ΔE, and/or the like.

As shown in FIG. 4E, and by chart 440, an example stackup is shown forthe sensor window. For example, a first side of the sensor window (e.g.,disposed on a first side of a substrate of the sensor window) mayinclude alternating high refractive index layers (H layers) and lowrefractive index layers (L layers) matched to an air interface. A secondside of the sensor window (e.g., disposed on a second side of thesubstrate of the sensor window) may include additional H layers and Llayers. In this case, each layer may be associated with a configuredthickness to provide optical performance described with regard to FIGS.4A-4D.

In this case, as shown in FIGS. 4A-4E, the sensor window enablestransmission at near-infrared wavelengths and color-selectivity atvisible wavelengths for a threshold range of angles of incidence,thereby improving performance relative to other techniques formanufacturing a colored window. Moreover, based on a reduced thicknessand sharper transition zone (e.g., a wavelength range from less than afirst threshold transmissivity and greater than a first thresholdreflectivity to greater than a second threshold transmissivity and lessthan a second threshold reflectivity is less than a threshold wavelengthrange), optical performance of a colored window and/or a sensorassociated therewith is improved.

As indicated above, FIGS. 4A-4E are provided merely as examples. Otherexamples are possible and may differ from what was described with regardto FIGS. 4A-4E.

FIGS. 5A-5D are diagrams of example characteristics relating to a sensorwindow described herein.

As shown in FIG. 5A, and by chart 500, a transmissivity may bedetermined for a sensor window and a particular spectral range. In thiscase, the sensor window may be a black-colored anti-reflectance sensorwindow disposed on a borosilicate substrate, matched to an airenvironment, and exposed to collimated light. Moreover, the sensorwindow is configured for a spectral range centered at 940 nm. As shown,at angles of incidence from approximately 0 degrees to approximately 45degrees, the transmissivity is less than 50% between approximately 400nm and approximately 850 nm and is greater than 95% at approximately 940nm. In this case, a blocker may be added to an optical filter thatincludes the sensor window to block transmission at, for example,greater than approximately 1000 nm, thereby suppressing transmission atwavelengths greater than approximately 1000 nm.

As shown in FIG. 5B, and by chart 510, a reflectance may be determinedfor the sensor window. In this case, the reflectance may be less than10% in the visible spectral range (e.g., from approximately 390 nm toapproximately 650 nm) and at angles of incidence from approximately 0degrees to approximately 45 degrees, resulting in a black color for thesensor window across the angles of incidence.

As shown in FIG. 5C, and by chart 520, a color shift at angles ofincidence from approximately 0 degrees to approximately 60 degrees isdetermined. For example, the sensor window is associated with a colorshift, at angles of incidence from approximately 0 degrees toapproximately 60 degrees, of approximately 30 ΔE, at angles of incidencefrom approximately 0 degrees to approximately 30 degrees of less than 5ΔE, and/or the like. In this way, as shown in FIGS. 5A-5C, the sensorwindow enables transmission at near-infrared wavelengths andcolor-selectivity at visible wavelengths for a threshold range of anglesof incidence, thereby improving performance relative to other techniquesfor manufacturing a sensor window.

As shown in FIG. 5D, and by chart 530, an example stackup is shown forthe sensor window. For example, a first side of the sensor window (e.g.,disposed on a first side of a substrate of the sensor window) mayinclude alternating high refractive index layers (H layers) and lowrefractive index layers (L layers) matched to an air interface. A secondside of the sensor window (e.g., disposed on a second side of thesubstrate of the sensor window) may include additional H layers and Llayers. In this case, each layer may be associated with a configuredthickness to provide optical performance described with regard to FIGS.5A-5C.

As indicated above, FIGS. 5A-5D are provided merely as examples. Otherexamples are possible and may differ from what was described with regardto FIGS. 5A-5D.

FIGS. 6A-6D are diagrams of example characteristics relating to a sensorwindow described herein.

As shown in FIG. 6A, and by chart 600, a transmissivity may bedetermined for a sensor window and a particular spectral range. In thiscase, the sensor window may be a red-colored anti-reflectance sensorwindow disposed on a borosilicate substrate, matched to an airenvironment, and exposed to collimated light. Moreover, the sensorwindow may be configured for a spectral range centered at 940 nm. Asshown, at angles of incidence from approximately 0 degrees toapproximately 45 degrees, the transmissivity is less than 50% betweenapproximately 400 nm and approximately 800 nm and is greater than 85% atapproximately 940 nm.

As shown in FIG. 6B, and by chart 610, a reflectance may be determinedfor the sensor window. In this case, the reflectance may be less than12% at a part of the visible spectral range (e.g., approximately 390 nmto approximately 590 nm) and at angles of incidence from approximately 0degrees to approximately 45 degrees. In contrast, the reflectance may begreater than 12% at another part of the visible spectral range (e.g.,approximately 590 nm to approximately 700 nm), resulting in a red colorfor the sensor window.

As shown in FIG. 6C, and by chart 620, a color shift at angles ofincidence from approximately 0 degrees to approximately 60 degrees maybe determined. For example, the sensor window is associated with a colorshift, at angles of incidence from approximately 0 degrees toapproximately 60 degrees, of 40 ΔE, at angles of incidence fromapproximately 0 degrees to approximately 30 degrees of less than 5 ΔE,and/or the like. In this way, as shown in FIGS. 6A-6C, the sensor windowenables transmission at near-infrared wavelengths and color-selectivityat visible wavelengths at a threshold range of angles of incidence,thereby improving performance relative to other techniques formanufacturing a sensor window.

As shown in FIG. 6D, and by chart 630, an example stackup is shown forthe sensor window. For example, a first side of the sensor window (e.g.,disposed on a first side of a substrate of the sensor window) mayinclude alternating high refractive index layers (H layers) and lowrefractive index layers (L layers) matched to an air interface. A secondside of the sensor window (e.g., disposed on a second side of thesubstrate of the sensor window) may include additional H layers and Llayers. In this case, each layer may be associated with a configuredthickness to provide optical performance described with regard to FIGS.6A-6C.

As indicated above, FIGS. 6A-6D are provided merely as examples. Otherexamples are possible and may differ from what was described with regardto FIGS. 6A-6D.

FIGS. 7A-7C are diagrams of example characteristics relating to a sensorwindow described herein.

As shown in FIG. 7A, and by chart 700, a reflectance may be determinedfor a sensor window and a particular spectral range. In this case, thesensor window may be a black-colored anti-reflectance sensor windowdisposed on a borosilicate substrate, matched to an air environment, andexposed to collimated light. Moreover, the sensor window may beconfigured for a spectral range centered at 1064 nm. In this case,reflectance may be less than 8% in the visible spectral range (e.g.,approximately 390 nm to approximately 700 nm) and at angles of incidencefrom approximately 0 degrees to approximately 45 degrees, resulting in ablack color for the sensor window.

As shown in FIGS. 7B and 7C, and by charts 710 and 720, respectively, acolor shift at angles of incidence from approximately 0 degrees toapproximately 60 degrees may be determined. For example, the sensorwindow is associated with a reduced color shift, at angles of incidencefrom approximately 0 degrees to approximately 60 degrees relative toother techniques for manufacturing a sensor window. In this way, asshown in FIGS. 7A-7C, the sensor window enables transmission atnear-infrared wavelengths and color-selectivity at visible wavelengthsat a threshold range of angles of incidence, thereby improvingperformance relative to other techniques for manufacturing a sensorwindow.

As indicated above, FIGS. 7A-7C are provided merely as examples. Otherexamples are possible and may differ from what was described with regardto FIGS. 7A-7C.

FIGS. 8A-8E are diagrams of example characteristics relating to a sensorwindow described herein.

As shown in FIG. 8A, and by chart 800, a transmissivity may bedetermined for a sensor window and a particular spectral range. In thiscase, the sensor window may be a blue-colored anti-reflectance sensorwindow disposed on a borosilicate substrate, matched to an airenvironment, and exposed to collimated light. Moreover, the sensorwindow may be configured for a spectral range centered at 940 nm. Asshown, at an angles of incidence from approximately 0 degrees toapproximately 45 degrees, the transmissivity is less than 15% betweenapproximately 400 nm and approximately 800 nm and is greater than 80% atapproximately 940 nm.

As shown in FIG. 8B, and by chart 810, a reflectance may be determinedfor the sensor window. In this case, reflectance may be less than 10% ata portion of the visible spectral range (e.g., approximately 500 nm toapproximately 700 nm). In contrast, the reflectance may be greater than90% at a spectral range less than approximately 500 nm, resulting in ablue color for the sensor window across a threshold range of angles ofincidence.

As shown in FIGS. 8C and 8D, and by charts 820 and 830, respectively, acolor shift at angles of incidence from approximately 0 degrees toapproximately 60 degrees may be determined. For example, the sensorwindow is associated with a color shift, at angles of incidence fromapproximately 0 degrees to approximately 60 degrees, of 105 ΔE, atangles of incidence from approximately 0 degrees to approximately 30degrees of less than 12 ΔE, and/or the like. In this way, as shown inFIGS. 8A-8D, the sensor window enables transmission at near-infraredwavelengths and color-selectivity at visible wavelengths at a thresholdrange of angles of incidence, thereby improving performance relative toother techniques for manufacturing a sensor window.

As shown in FIG. 8E, and by chart 840, an example stackup is shown forthe sensor window. For example, a first side of the sensor window (e.g.,disposed on a first side of a substrate of the sensor window) mayinclude alternating high refractive index layers (H layers) and lowrefractive index layers (L layers) matched to an air interface. A secondside of the sensor window (e.g., disposed on a second side of thesubstrate of the sensor window) may include additional H layers and Llayers. In this case, each layer may be associated with a configuredthickness to provide optical performance described with regard to FIGS.8A-8D.

As indicated above, FIGS. 8A-8E are provided merely as examples. Otherexamples are possible and may differ from what was described with regardto FIGS. 8A-8E.

In this way, a sensor window may be color-matched to, for example, anadjacent surface (e.g., a body color of a vehicle), such as within 1 ΔE,within 5 ΔE, within 10 ΔE, within 20 ΔE, within 30 ΔE, within 40 ΔE,within 100 ΔE, within 150 ΔE, and/or the like for angles of incidencefrom approximately 0 degrees to approximately 60 degrees or greaterangles of incidence with reduced thickness, improved transmissivity,and/or the like relative to a pigment based sensor window. Moreover, thesensor window may enable a sharper transition between transmissivity ata sensing spectral range and color-selectivity at a visible spectralrange, thereby improving sensing by a sensor element relative to apigment based sensor window.

The foregoing disclosure provides illustration and description, but isnot intended to be exhaustive or to limit the implementations to theprecise form disclosed. Modifications and variations are possible inlight of the above disclosure or may be acquired from practice of theimplementations.

Some implementations are described herein in connection with thresholds.As used herein, satisfying a threshold may refer to a value beinggreater than the threshold, more than the threshold, higher than thethreshold, greater than or equal to the threshold, less than thethreshold, fewer than the threshold, lower than the threshold, less thanor equal to the threshold, equal to the threshold, and/or the like.

Even though particular combinations of features are recited in theclaims and/or disclosed in the specification, these combinations are notintended to limit the disclosure of possible implementations. In fact,many of these features may be combined in ways not specifically recitedin the claims and/or disclosed in the specification. Although eachdependent claim listed below may directly depend on only one claim, thedisclosure of possible implementations includes each dependent claim incombination with every other claim in the claim set.

No element, act, or instruction used herein should be construed ascritical or essential unless explicitly described as such. Also, as usedherein, the articles “a” and “an” are intended to include one or moreitems, and may be used interchangeably with “one or more.” Furthermore,as used herein, the term “set” is intended to include one or more items(e.g., related items, unrelated items, a combination of related items,and unrelated items, etc.), and may be used interchangeably with “one ormore.” Where only one item is intended, the term “one” or similarlanguage is used. Also, as used herein, the terms “has,” “have,”“having,” and/or the like are intended to be open-ended terms. Further,the phrase “based on” is intended to mean “based, at least in part, on”unless explicitly stated otherwise.

What is claimed is:
 1. A sensor window comprising: a first set of layers; and a second set of layers, the first set of layers and the second set of layers being configured to: pass near-infrared light; and reflect one or more colors that match a surface adjacent to the sensor window.
 2. The sensor window of claim 1, further comprising: a substrate matched to an air environment.
 3. The sensor window of claim 1, wherein the sensor window is hidden from view based on the one or more colors being reflected.
 4. The sensor window of claim 1, wherein the sensor window enables a sensor to transmit the near-infrared light and receive reflected near-infrared signal without the near-infrared light being blocked by the sensor window.
 5. The sensor window of claim 1, wherein the first set of layers comprise a high refractive index material that has a refractive index of greater than approximately 3.0.
 6. The sensor window of claim 1, wherein the second set of layers comprise a low refractive index material that has a refractive index of less than approximately 2.7.
 7. The sensor window of claim 1, wherein the first set of layers comprise a high refractive index material that has a first refractive index, wherein the second set of layers comprise a low refractive index material that has a second refractive index, and wherein a difference between the first refractive index and the second refractive index is greater than approximately 1.5.
 8. The sensor window of claim 1, wherein the first set of layers are different from the second set of layers, and wherein the first set of layers alternate with the second set of layers.
 9. A system comprising: a sensor; and a sensor window configured to: pass near-infrared light; and reflect one or more colors that match a surface adjacent to the sensor window.
 10. The system of claim 9, wherein the sensor is configured to perform a measurement of the near-infrared light.
 11. The system of claim 9, wherein the near-infrared light is reflected toward the sensor.
 12. The system of claim 9, wherein the sensor window comprises: high refractive index material layers that have a first refractive index, and low refractive index material layers that have a second refractive index, wherein a difference between the first refractive index and the second refractive index is greater than approximately 1.5.
 13. The system of claim 9, wherein the one or more colors are one or more colors of a first light, of a first portion of an input optical signal, that is reflected in a manner that causes the sensor window to appear as a particular color of the surface, and wherein the first portion of the input optical signal further comprises second light that is absorbed.
 14. The system of claim 13, wherein the near-infrared light is a second portion of the input optical signal.
 15. The system of claim 9, wherein the sensor window is associated with multiple component filters that are associated with multiple spectral ranges.
 16. The system of claim 9, wherein, based on a varying thickness of the sensor window, different portions of the sensor window pass different wavelengths of light to different sensor elements of the sensor.
 17. The system of claim 9, wherein the sensor is configured to provide an output electrical signal based on the near-infrared light.
 18. A sensor window comprising: a substrate; a first side, disposed on the substrate, comprising: a first set of layers, and a second set of layers; and a second side, disposed on the substrate, comprising: a third set of layers, and a fourth set of layers, the substrate, the first side, and the second side being configured to: pass near-infrared light; and reflect one or more colors that match a surface adjacent to the sensor window.
 19. The sensor window of claim 18, wherein the first set of layers comprise a high refractive index material that has a first refractive index, wherein the second set of layers comprise a low refractive index material that has a second refractive index, and wherein the first refractive index is higher than the second refractive index.
 20. The sensor window of claim 19, wherein the third set of layers comprise the high refractive index material, and wherein the second set of layers comprise the low refractive index material. 